Elastic fabrics



mo N E L B m UY CA PR m (I) ELASTIC (2) POLYPROPYLENE-RAYON BLEND INVENTOR. HAROLD W. CON ANT ATTORNEY -age problem because 'both cotton and rayon United States Patent Office e &199548 Patented Aug. 10, 1965 %89,548 ELATEC FABRICS Harod W. Conant, Southampton, Mess., assignor to United Elastic Corporation, Easthampton, Mass., a corporation of Massaehusetts Filed May 2, 1963, Ser. Ne. 277,453 4 Clains. (Ci. 139-421) This invention relates to improved elastic fabrics.

Elastic fa-brics, for example webbings, are normally prepared by weaving elastic threads, for example cut rubber, extruded latex rubber, polyurethane elastomers and the like with a filling thread of textile fibers. It is also common practice in elastic fabrics to wrap the elastic cores with textile threads, either by helical winding, braiding or the like, in order to control the physical characteristics. Since webbing is used frequently in articles such as girdles, support bandages, elastic inserts in garments such as shorts and the like, it is practically standard to use covered elastic threads.

While there is thoreticaliy no limit on the textile threads which can be used for covering and filling, -by far the most common are cotton threads or yarns or spun rayon yarns, these are cheap, have a very desirable feel and are generally accepted as the standard textile yarns to be used.

Partcularly when webbing is in use two problems are presented among others. The -first problem is a shrinkshare the common characteristic of cellulosic yarns of shrinking when washed and dried. The elastic core which is wrapped or covered, of course does not shrink and therefore it is desirable to have as little shrinkage as possible in the textile thread. It is true that the thread is wrapped or braided as a covering and so there is a certain amount of elasticity -but this is considerably less than the elastic core itself. Shrinkage is therefore undesirable but a very considerable amount of shrirkage, just under is unavoidable with standard cotton wrapping yarns. This has been accepted as an unavoidable evil in the art but is not wanted.

The second problem is presented by the elastic Webbing or fabric itself It is common to have a filling yarn of cotton or rayon and this presents a problem of abrasion at the edges of the fabric where the filling threads are sharply bent and come in contact with the body or other surfaces which can cause abrasion. This is a serious problem because -if the edges start to abrade there Will be frayed filling threads which are both unacceptable from the standpoint of appearance and which also do not feel as comfortable to the wearer of the elastic fabric. Also when a filling thread is cut or rather abraded through it tends to run and in general when the edges have become seriously abraded web-bing is no longer useful even though its elastic threads may still have many months of useful life in them. The above two problems have been very serious ones in the elastic fabric art and it is with a solution or rather an enormous improvement that the present invention deals.

According to the present invention instead of using cotton or pure spun rayon for wrapping yarns and for filling threads a -spun blend of polypropylene and rayon is used. The ranges of practical usefulness are definite but they are quite wide, substantial improvement being obtained With as little as 10% polypropylene and reaching a maximum near 40% which does not greatly change With still more polypropylene. For other reasons it is generally undesirable to use more than 50% polypropylene as larger proportions begin to affect the desirable hand of the fabric. Another factor of course is that the polypropylene is in general more expensive than the rayon and so it is economically preferable to use as small a percentage as will give satisfactory results. t

The invention is of course not limited to spun rayon as the cellulosic constituent of the blend, cotton may also be used but since spun rayon produces a very excellent hand and at present is no more expensive than cotton it is preferred in the present invention.

It is an advantage of the present invention that it in no way atfects the normal elastic yarn covering manufacring techniques -or the weaving of elastic fabrics. The improved result-s of the invention are obtained without any cost in -gpeater mechanical Complexity or in cost of weaving or covering. p

The nature of the elastic core itself does not appear to have any part in the improvements of the present invention. In other words the same mprovernents are obtained when the basic elastic core is rubber, either cut or extruded, polyurethane and the like. Accordingly the invention will be described in conjunction with specific examples in which rubber cores are used. This is illustrative only and in no sense limits the use of the invention to -fabrics prepared with rubber cores. In the specific examples, the percentages are by weight.

The invention is .also illustrated in conjunction with the drawing which shows a typical fabric in diagrammatic form.

Example 1- An elastic webbing is prepared using warp threads (l) of rubber having a core of approximately 1400 yds. per lb. covered with a double spiral wrapping (2) of textile thread -spun from a blend of polypropylene and 87.5 rayon fibers. A filling yarn (3) of approximate ly 8400 yds. per lb. of the same blend is used. There were 60 filling threads per inch.. v

A second webbing was then .prepared in which the wrapping and filling yarns Were 100% cotton of the same yarn size. This webbing will be referred to in this and subsequent examples as the cotton control fabric.

Both webbings were then subjected to ordinary laundering under standard laundering conditions set out in the AATCC Technical Manual. Shrinkage was then measured in the ordinary manner. The cotton control webbirg shrank The webbing with the polypropylene-spun rayon blend shrank 9.5 that is to say the shrinkage was about two-thirds that of the control webbing.

Example 2 The procedure of Example 1 was repeated except that the polypropylene-rayon blend was 25% polypropylene and 75% rayon. Shrinkage after laundering was 7.5 that is to say the shrinkage was slightly over one-half of the control webbing.

Example 3 The procedure of Example 1 was repeated but the polypropylene-rayon blend was 375% polypropylene and 625% rayon. The shrinkage was 55%, that is to say the shrinkage was about 38 percent that of the control webbing.

Example 4 The procedure of Example 1 was repeated using a polypropylene-rayon blend of equal amounts. The shrinkage Was 55%, that is to say the shrinkage was about 38 percent that of the control webbing.

It will be apparent that the minimum shrinkage is reached Somewhere between '25 and 37.5 polypropylene and this minimum shrinkage remains the same even with much larger arnounts of polypropylene. This is a most surprising result. If it were assumed, which would be ordinariiy expected, that the shrinkage was reduced by the presence of the polypropylene one would expect that the shrinkage would continue to be reduced as larger and larger amounts of polypropylene were used. Why there is no decrease in shrinkage beyond 375% polypropylene is completely inexplcable. It is not known why this result is obtained and it is not desred to limit the present invention to any theoretical explaation except that it is obviously not an average of the properties of polypropylene alone and rayon alone. The more than 2 /2 times greater shrinkage with cotton yarn is obviated without any undesirable loss in hand, the webbings of the four examples being completely acceptable by industry standards when compared to cotton wrapping yarrs. In other words the improved shrinkage is obtained with no loss in other desrable properties.

The webbing of Example 3 and control cotton webbing With 100% cotton filling yarns were tested for edge abrasion by the Accelerotor described in the AATCC Technical Manual test method 93-1959. This is an enormously accelerated test which in a few minutes simulates abrasion of many months or even years of normal use. The initial abrasion was approximately the same for the polypropylene-rayon blend and the cotton control fabric, namely 3 to 4 minutes. A range is given because the test is ordinarily carried out several times and an average taken or the range noted.

The webbings were then subjected to ten launderings, that is to say ten automatic washings with hypochlorite bleach and ten tumble dryings. Washings and dryings were carried out in the ordinary test form of AATCC and were absolutely uniform for the two fabrics. After the tenth laundering and drying .the abrasion tests were repeated. Surprisingly the webbing of Example 3 showed an increased abrasion resistance of from 5.5 to 7 minutes. The cotton control fabric retaned its initial 3 to 3 /2 minutes abrasion time. In other words, after laundering the polypropylene blend had increased its abrasion resistance practically 100%, i.e. the webbing of the present invention has shown wear twice as long as;

ordinary webbing as far as edge abrasion is concerned. It is not understood why this great increase in abrasion resistance is obtained by laundering and no explanation or mechanism is advanced as to why this should take place, It is a most unusual phenomenon in textile fabrics and it is not desired to limit the present invention to any theory of operation. The facts however show a great increase in abrasion resistance and since the materials are almost always used in garments which are frequently laundered, this is the normal condition for regular wear.

Initial abrasion resistance is of little importance because garments are laundered many times before they would reach the point where edge abrasion Would have rendered them useless in the case of cotton yarns.

I claim:

1. An elastic fabric of covered elastic warp threads having elastic cores and textile filling threads, said covered elastic threads comprising a cover of threads of a blend of from 10 to percent staple polypropylene with the balance staple cellulosic fiber, whereby said fabric has a shrnkage in the warp direction on laundering rcduced to not more than about two-thirds that of fabrics having elastic warp threads covered with cotton.

2. An elastic fabric according to claim 1 in which the cellulosic fiber is rayon.

3. An elastic fabric according to claim 2 in which the filling threads are of a blend of 10 to 50 percent staple polypropylene and the balance spun rayon whereby said fabric has a greatly increased edge abrasion resistance after repeated launderings as Compared with fabrics having all cellulosic filling threads.

4. An elastic fabric accordiny to claim 3 in which the elastic core is rubber.

References Cited by the Examier UNITED STATES PATENTS 2,643,686 6/53 Richards 139-421 2,760,330 8/56 Lowney 57-152 X 2,974,559 3/61 Goggi. 3,0l3, 379 -12/61 Breen 57- 3,015, 1/62 Fior 28-1 3,068,636 12/62 Masurel 28-1 3,l01,522 8/63 Hopper et al 57-140 X FOREIGN PATENTS 1,282,388 12/61 France.

390997 4/ 33 Great Britain.

%76,928 9/ 61 Great Britain.

887,673 l/ 62 Great Britain.

OTI-IER REFERENCES Kardos, A.: "Latest Word'on Making Elastic Fabrics- Part I, Textile World, Pages 49-53 relied on, March, 1963.

Kardos, A.: Latest Word on Making Elastic Fabrics- Part II, Textile World, Pages 57-59 relied on, April, 1963.

DONALD W. PARKER, Pr'mary Exam'ner. 

1. AN ELASTIC FABRIC OF COVERED ELEASTIC WARP THREADS HAVING ELEASTIC CORES AND TEXTILE FILING THREADS, SAID COVERED ELASTIC THREADS COMRPSING A COVER OF THREADS OF A BLEND OF FROM 1/ TO 50 PERCENT STAPLE POLYPROPYLENE WITH THE BALANCE STAPEL CELLUSLOIS FIBER, WHEREBY SAID FABRIC HAS A SHRINKAGE IN THE WAY DIRCTION ON LAUNDERING REDUCED TO NOT MORE THAN ABOUT TWO-THIRDS THAT OF FABRICS HAVING ELASTIC WARP THREADS COVERED WITH COTTON. 